Rheostat mechanism



Nov. 30 1926.

c. AALBORG RHEosTAT MEoH'ANxsM Filed March 25, 1920 wlTNEssEs;

Patented Nov. 30, 1926.

UNITED STATES PATENT orifice.

CHRISTIAN AALBORG, OF FITTSBURGH, PENNSYLVANIA, ASSIGNOR TO WESTING- HOUSE ELECTRIC & MANUFACTURING COMPANY, A CORPORATION OF PENNSYL- VANIA.

RHEOSTAT MECHANISM.

` My invention relates 'to rheostat mechanisms and particularly to motor-operated rheostat mechanisms.

One object of my invention is to provide' a rheostat mechanism of the above-indicated character that shall be simple, compact and relatively inexpensive in construction, and that shall have the propelling motor supported along the axis of rotation of the rheostat contact arm.

In many electrical systems now in service, a motor-operated rheostat is used to vary the resistance value of various circuits. Thus, in many types of regulator systems, motor-operated rheostats are provided for varying the excitation of the generators conneet-ed to the main supply circuit and regu lators are provided for governing the operation of the motors in accordance with the electrical conditions obtaining on the supply circuit.

In a rheostat mechanism constructed in accordance with my invention, the various contact terminals are arranged in concentric g5 circles and a rotatable contact arm is provided with brush members which engage the contact members. The brush members are so supported on the contact arm as to be movable perpendicularly into engagement with the contact members. Spring members are provided for biasing the brush members into engagement with the contact members. A stop member is provided inthe path of the contact arm for limiting the movement of such arm. A motor is supported along the axis of rotation of the contact arm and is mechanically connected to such arm by a worm-gear mechanism and an overrunning clutch. The overrunningV clutch permits the free rotation of the motor when the contact arm engages the above mentioned stop member. The leads which are connected to the motor are preferably carried through a base plate of the device. and through the supporting member for the motor at the center of rotation of the contact arm.

In the accompanying drawing, Figure l is a front elevational View of a rheostat mechanism constructed in accordance with my invention; Fig. 2 is a sectional elevational view of the mechanism shown in Fig. 1; Fig. 3 is a sectional view of the worm gearing between the motor and the contact arm; Fig. 4 is a'detail view of one of the Serial No. 368,137.

brush members; Fig. 5 is a plan view of the supporting trame for the brush members; Fig. 6 is a side elevational view of the supporting frame; Figs. 7 and 8 are detail views of a spacing member for the brush members; Figs. 9, 10 and 11 are detail views of one of the brush members, and Fig. 12 is a detail View of a terminal cap. v

Referring particularly to Figs. 1, 2 and 3 of the drawing, a vsupporting base 1, composed ot any suitable insulating material, is provided for supporting contact members 2 which are disposed in concentric circles 3, 4 and 5. A contact ring 6 is mounted upon the base 1 adjacent to the inner row 5 of con tact members and within the ring 6 is mounted a row of contact members 7 and a contact ring 8. A contact arm 9 is provided for engaging the contact members and the contact rings, and a motor 1() is provided for operating the contact arm 9.

The Contact arm 9 comprises a supporting member 11, which has a bearing upon a hollow shaft 12, and a brush mechanism 13 Which is connected tothe supporting member 11. The arm 9 may be manually actuated by a handle 9a forming a part thereof. The conductor leads for the motor extend through the shaft 12 which is fitted to a supporting plate 14 and is held in position by a nut 15. rIhe supporting plate 14 is mounted upon one side of the base member 1 and is connected to a second supporting plate 16 on the opposite side ot the base member by means of any suitable bolts or rivets 17. The plate 14 is provided with a projecting portion 18 which is engaged by a lug 19 on the arm 9 to limit the movement of such arm.

The brush mechanism 13, which is shown more in detail in Figs. 5 to 12, inclusive, comprises a supporting block 20, of any suitable insulating material, preferably balrelite micarta, which is connected, in any suitable manner, to the supporting arm 11. The brush member 21, which engages the contact ring 8 and the contact members 7, is connected to the insulating block 20 in any suitable manner, as by screws 22. A brush frame 23 is connected to the outer end of the insulating blo-ck 2O and serves to support the brush members 24, 25, 26 and 27, which respectively engage the contact members of rows 3, 4, and 5 and the Contact ring 6. The frame 23 comprises two members 28 means adapted to limit the angular movement of the Contact arm and a clutch interposed between the motor and Contact arm, said clutch including a rigid clutch member provided With a friction face and a second clutch member resiliently retained continuously in engagement with said rigid clutch member, thereby to permit independent rotation of the motor when the Contact arm is held against angular movement.

4. In a rheostat mechanism, the combination with a plurality of Contact members, a rotatable Contact arm for engaging said contact members, and a stop member for limiting the movement of the Contact arm, of a motor supported along the a-.Xis of rotation of said Contact arm, and means comprising a plurality of yeldingly mounted balls for yieldingly connecting the motor to the Contact arm to permit the rotation of the motor When the arm engages said stop member.

In testimony whereof, I have hereunto subscribed my name this 13th day of March, 1920.

CHRISTIAN AALBORG. 

